Spirit SX - Noisy Aux Sends

[Paul TC]

Question for any Spirit SX users, having searched there are a number of users here, who I hope can comment.

 

Are the Aux Sends on this desk particularly noisy ?

 

Unfortunatly I have access at presnt to only the one example of this desk so cannot make any comparissons.

 

I am looking at an installation where a post fade Aux Send is being used to feed an induction loop driver.

 

The signal from the Main Outs is clean, and no problem, but the signal from the Aux Send contains a lot of HF hiss. More than I would consider acceptable.

 

Inputs are unbalanced line leve to mono inputs, (Radio Mic RX's) each input gain near max (85%),

 

all eq flat, channel fader at 0 and the aux send levels are set at 75% on

both channel and master.

 

Output is balanced feed to line input of loop amp.

 

Any specific comment welcome.

[Lamplighter]

Paul

 

I've used several SXs over the years, never found the auxes to be noisy.

I would set it up as you suggested, check that the input is giving a decent level on PFL then if the output (aux) is still noisy try removing the input to remove any doubt about the source. Also compare the PFL of the source with AFL of the aux in question. They should sound the same if your gain settings are correct.

 

Brian

[Pete Alcock]

Paul,

 

I concur with Brian. I have several Spirit desks and the outputs are as quiet as you'd expect - as good as most high-end desks anyway.

 

What's the output like from the other Aux's? Also, have you tried switching the Aux between post and pre (level should be the same if the channel fader is at "0"). If there's a difference in hiss, check that all the channels behave the same. If you find one particular channel or one Aux output which is noisier, then you've pinned down the likely culprit - probably a duff op-amp.

 

Servicing is fairly specialised as most components are surface mount. Not for the faint-hearted (or those with fat soldering iron tips).

 

Pete.

[Bobbsy]

Put me down as somebody else who's never had problems with SX aux feeds.

 

Perhaps a silly question, but have you listened to the output on anything else other than the induction loop? If not, I think my first try might be to swap the outputs and listen to the aux on your FOH setup (or any other "known to be good" form of monitoring.

 

If it's clean there, then the problem is probably to do with gain structure and/or the induction system. If the hiss moves to the FOH, then you may have a board fault.

 

Bob

[3guk]

I have an SX right infront of me now and there are no problems with any of the au sends.